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... power density. This is emitted uniformly in all directions and though not nearly as
powerful as the amplified photon flux of frequency v, it requires a filter to remove it from
the amplified signal.
Astrophysical masers also resemble random lasers in that, unlike conventional
masers and lasers, the ...

... • The detailed light curve is unlike that of a supernova, nova, or any other type of variable star (1,2,3). During the outburst, V838 Mon was found to have a maximum effective temperature
of an A – F star at the optical maximum in February 2002. The effective temperature then cooled to a very low ~8 ...

... background of this poster and the color picture below) ACS showing what is interpreted as a “light echo” from the eruption (1). A summary of the of the major results of observations since
the eruption are:
• The detailed light curve is unlike that of a supernova, nova, or any other type of variable ...

... Velocities are usually calculated respect to the Local Standard of Rest (LSR), an ideal
point in rotation around the Galactic centre as far as the Sun.
The relationship between velocity and frequency is:
...

... Sgr B2 (M) are also the only H2 CO maser sources with corresponding SiO maser detections and vice versa, though the sample of regions explored in both tracers is small.
This high detection rate of masers in star-forming regions
within the CMZ, despite limited statistical information, suggests that H ...

... • The methodology is to combine the initial mass
function with the star formation law in the Galaxy
(as a function of position) to create a distribution
of massive stars as a function of galactic longitude.
• Then, assuming that every massive star excites a
methanol maser during its birth, one can d ...

... full polarization monitoring of SiO masers, sampling at least once per hour, with
high spatial resolution. This will ultimately allow us to distinguish between the
proposed scenarios and to investigate the fate of inner planetary systems around
solar-type stars entering their AGB phase.
All our know ...

... Positions for one 12 GHz maser spot in
W3OH relative to 3 background sources
(offset from each other for clarity). The data
show the sinusoidal parallax signature
superposed on the proper motions.
...

... collapse of a cool molecular cloud.
In the final stages of this collapse, the cloud’s core becomes
sufficiently hot and the gas is under enough pressure for fusion
reactions to begin: this is a young stellar object (YSO), a baby
star.
Obviously, astronomers are very interested in the stages of the
c ...

... A rough analysis of the transfer equation shows that
intensity is amplified exponentially.
The brightness temperature of a maser transition can be extremely high.
For example, for Tex= -20 K, |τ0| = 20, we have T0 = 1010 K.
Maser radiations is produced in very compact regions (maser spots),
and the ...

... Atomic emissions beyond the
visible spectrum
• Note that the emission extends over a range
of frequencies.
• The term often refers to the visible light
emission spectrum, although it extends to the
whole electromagnetic spectrum, from the
low energy radio waves up to high energy
gamma rays.
...

... the spectrum, this corresponds to a line shift on the order of 1.5 angstroms. This shift
could be easily detected, yet, for many years, no deuterium was ever detected in any
astronomical object. In contrast, the terrestrial abundance of deuterium is readily
measured and is roughly 2x10-4 by fraction ...

... the sky.
An old UKST Hα plate which includes the PN region exists
in the archive. This exposure (HA2307) was taken in 1976 for John
Meaburn on fast but coarse-grained O-9804 emulsion with a mo-
...

... Tau 6 and FU Tau A with high angular resolution observations with the Plateau de
Bure Interferometer (PdBI). These sources were chosen because their associated CO
emission showed clear evidence of an outflow and / or their spectral energy distributions
(SEDs) showed strong evidence of a massive accr ...

... Extinction was known since 1847 (though
not taken seriously in Galaxy models)
 Reddening discovered by Trumpler (1930)
 Wavelength dependence established
obscuration as due to small particles
 Reddening proportional to NH
...

... that the disk’s total luminosity is LD = 2πh2R I(R = 0).
For the Milky Way, LD ≈ 1.5 × 1010 L in the V band and hR ≈ 4 mathrmkpc. Show
that the disk’s surface brightness at the Sun’s position, 8 kpc from the Galactic Center, is
∼ 20 L pc−2 . The mass density in the disk is 40 − 60 M pc−2 , so M/L ...

... much, so molecular gas clouds can be detected
even though there may be other gas and dust
clouds in the way.
These clouds are mostly molecular hydrogen,
which unfortunately does not emit in the radio
portion of the spectrum.
Other molecules present: CO, HCN, NH3, H2O,
CH3OH, H2CO, and more than a hu ...

... from the hot ionized gas. In order to understand from which part of the sun’s
atmosphere this emission arises, one needs to understand the main opacity
source at radio wavelengths. (The opacity is a measure of how much a wave
gets absorbed as it travels through a medium). The main source of opacity ...

Astrophysical maser

An astrophysical maser is a naturally occurring source of stimulated spectral line emission, typically in the microwave portion of the electromagnetic spectrum. This emission may arise in molecular clouds, comets, planetary atmospheres, stellar atmospheres, or various other conditions in interstellar space.